Rotary disc filter with automatic integrated backwash and chemical cleaning system

Patent metadata

Field	Value
Publication number	US-9962635-B2
Application number	US-201414775196-A
Country	US
Kind code	B2
Filing date	Mar 11, 2014
Priority date	Mar 14, 2013
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

A rotary disc filter is provided with an integrated backwash and chemical cleaning system. In one mode of operation, backwash is directed through a control valve to one or more nozzles for spraying the backwash onto the filter media forming a part of a rotary disc filter. In a second mode, a chemical cleaning mode, the pump directs backwash through an eductor that induces a chemical into the inductor which is mixed with the backwash to form a backwash-chemical mixture that is sprayed onto the filter media. A control system is used in conjunction with the backwash and cleaning systems to monitor process information and/or filter media properties and to determine when to perform backwashes and regenerative cleanings in order to optimize the performance of the filter system.

First claim

What is claimed is:

1. A rotary disc filter having a filter media cleaning system operable in a first mode for backwash cleaning the filter media and in a second mode for chemically cleaning the filter media, the rotary disc filter comprising:
a drum including an inlet opening for enabling influent water to flow into the drum;
a series of rotary filter discs mounted on the drum;
filter media positioned on opposite sides of the disc;
the drum including openings in the surface thereof for enabling influent water to flow by gravity from the drum into the disc where the influent water accumulates therein and moves from the interior of the disc outwardly through the filter media to produce filtered water;
an integrated filter media cleaning system operable in the first mode to backwash the filter media by directing the backwash onto the filter media and operable in the second mode to chemically clean the filter media;
the integrated filter media cleaning system including a control valve, a backwash supply line leading from the control valve to one or more nozzles, an eductor operatively interconnected between the control valve and the one or more nozzles and further operatively connected to a chemical reservoir through a chemical feed line;
characterized by comprising:
a single pump operative in the first mode to pump a backwash through the control valve and through the backwash supply line to the one or more nozzles, and further operative in the second mode to pump the backwash through the control valve into the eductor which mixes the backwash with a chemical from the chemical reservoir to form a backwash-chemical mixture and wherein the pump is operative to pump the backwash-chemical mixture to the one or more nozzles;
a controller for controlling the cleaning system and causing the cleaning system to operate in the first mode under certain conditions and to operate in the second mode under other conditions by implementing the following functions:
i. execute backwash cleaning of the filter media according to the established protocol for backwash cleaning of the filter media while the rotary disc filter is conducting filtration of the influent water;
ii. receiving variable process data for a selected period of time;
iii. on an ongoing basis, evaluating the received variable process data;
iv. comparing the evaluated variable process data with model process information;
v. based on the differences between the evaluated variable process data and the model process information, determining whether to cause the cleaning system to chemically clean the filter media; and
vi. if the difference between the evaluated variable process data and the model process information calls for implementing chemical cleaning of the filter media, then while the rotary disc filter is filtering influent water instituting chemical cleaning of the filter media of the rotary disc filter.

2. The rotary disc filter of claim 1 wherein the controller functions to quantify the difference between the evaluated variable process data and the model process information, and if the difference is greater than a threshold, then the controller is operative to cause the cleaning system to chemically clean the filter media.

3. The rotary disc filter of claim 1 wherein the controller functions to suspend backwash cleaning of the filter media while the cleaning system operates to chemically clean the filter media.

4. The rotary disc filter of claim 1 wherein prior to instituting chemical cleaning of the filter media, the controller institutes backwash cleaning of the filter media.

5. The rotary disc filter of claim 1 wherein the controller controls the cleaning system such that when the cleaning system is operated to chemically clean the filter media, only a portion of the filter media is chemically cleaned at one time; and wherein the controller further functions to rotate the disc such that a different portion of the filter media can be chemically cleaned.

6. The rotary disc filter of claim 1 wherein the controller receives and evaluates variable process data while chemically cleaning the filter media, and wherein in response to the variable process data indicating a need for backwash cleaning of the filter media, the controller functions to suspend chemical cleaning and causes the cleaning system to perform backwash cleaning of the filter media.

7. The rotary disc filter of claim 1 wherein the variable process data received by the controller includes solids loading and backwashing runtimes.

8. The rotary disc filter of claim 7 wherein the model process information includes information correlating solids loading with recommended backwash runs.

9. The rotary disc filter of claim 1 wherein the controller functions to initiate chemical cleaning of the filter media if backwash runtimes for the solids loading being experienced by the disc filter is below a threshold requirement suggested by the model process information.

10. The rotary disc filter of claim 1 wherein the controller controls chemical cleaning of the filter media such that chemical cleaning occurs between backwash cycles, and wherein the backwash cycles may occur at programmed times or result from a variable process based program.

11. The rotary disc filter of claim 1 wherein during chemical cleaning if the controller determines that process conditions requires backwash cleaning, the controller is configured to (1) recognize what portions of the filter media have been chemically cleaned, (2) suspend the chemical cleaning activity while backwash cleaning is performed, and (3) resume chemical cleaning activity for unclean portions of the filter media once the backwash cleaning is complete.

12. The rotary disc filter of claim 1 including two sets of spray nozzles wherein one set includes at least one nozzle operatively connected to the backwash supply line for spraying a backwash on the filter media, the other set including at least one nozzle operatively connected to a chemical supply line for spraying the backwash-chemical mixture onto the filter media.

13. The rotary disc filter of claim 1 wherein the controller controls the amount of chemical induced into the eductor and mixed with the backwash.

14. The rotary disc filter of claim 1 wherein the controller during chemical cleaning is operative to cycle the pump on and off and to rotate the disc in intervals and to provide for a rest period to allow the chemical to contact the filter media.

15. The rotary disc filter of claim 1 wherein the integrated filter media cleaning system comprises two separate sets of nozzles, a first set of nozzles and second of set of nozzles; and wherein the backwash supply line is operatively connected to the first set of nozzles and wherein there is provided a backwash-chemical mixture supply line that leads from the eductor to the second set of nozzles.

16. A rotary disc filter having a filter media cleaning system operable in a first mode for backwash cleaning the filter media and in a second mode for chemically cleaning the filter media, the rotary disc filter comprising:
a drum including an inlet opening for enabling influent water to flow into the drum;
a series of rotary filter discs mounted on the drum;
filter media positioned on opposite sides of the disc;
the drum including openings in the surface thereof for enabling influent water to flow by gravity from the drum into the disc where the influent water accumulates therein and moves from the interior of the disc outwardly through the filter media to produce filtered water;
an integrated filter media cleaning system operable

Assignees

• Veolia Water Solutions & Tech

Inventors

• Stewart Mark H
• Wood Luke
• Casey Todd
• Palumbo Ronald V
• Strube Rune

Classifications

• B01D2201/085

  using another chemical than the liquid to be filtered · CPC title

• B01D33/804

  integrally combined with devices for controlling the filtration · CPC title

• B01D2201/084

  Nozzles placed on the filtrate side of the filtering element · CPC title

• B01D33/48 Primary

  by flushing, e.g. counter-current air-bumps · CPC title

• B01D33/50 Primary

  with backwash arms, shoes or nozzles · CPC title